• 대한금속재료학회지
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• 제47권3호
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• pp.195-201
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• 2009

This paper is concerned with effects of Mn and heat-input on the mechanical properties of EGW welds. Four different kinds of welding consumables were fabricated by varying Mn contents such as 1.3, 1.5, 1.7, 2.0%Mn and each consumable was welded for EGW on four heat-input conditions between 190 and 340 KJ/Cm. Mn contents were decreased as heat-input increases and alloy elements (C, Si, Ti, B, Al) to deoxidize easily also revealed similar tendency to Mn. Their microstructure, Charpy impact property and strength were investigated, and it is found that Charpy impact property and strength exhibit a strong dependence on change of microstructure by Mn contents and heat-input. The increase of Mn contents or the decrease of heat-input made the microstructure fine and increase volume fraction of acicular ferrite, thereby leading to the great improvement of Charpy impact property and strength. In case of single EGW, optimum Mn contents are over 1.7% for the toughness and strength.

• The Journal of Asian Finance, Economics and Business
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• 제10권2호
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• pp.183-193
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• 2023

This paper proposes and examines the economic impact of infrastructure improvement on the San-En-Nanshin region in the Chubu area of Japan. We develop a single transportation computable general equilibrium (CGE) model for each subregion within the San-En-Nanshin region. The explicit modeling of the transportation infrastructure is defined based on interregional commuting flows and business trips, considering the spatial structure of the San-En-Nanshin economy. A CGE model is integrated with an interregional transportation network model to enhance the framework's potential for understanding the infrastructure's role in regional development. To evaluate the economic impact of transportation improvement, we analyze the interrelationship between travel time savings and regional output and income. The economic impact analysis under the CGE framework reveals how transportation facilities and systems affect firm and household behavior and therefore induce changes in the production and consumption of commodities and transportation services. The proposed theoretical model was tested by using data from the 2005 IO tables of each subregion and the 2006 transport flow dataset issued by the Ministry of Land, Infrastructure, Transport, and Tourism in Japan. As a result, the paper confirms the positive effect of transportation investment on the total output and income of the studied region. Specifically, we found that while economic benefits typically appear in urban areas, rural areas can still potentially benefit from transportation improvement projects.

• The Journal of Asian Finance, Economics and Business
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• 제9권2호
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• pp.437-448
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• 2022

The impact of supervisory communication apprehension (SCA) on subordinates' job performance was investigated in this study. We also examined the impact of task-related uncertainty in mediating the relationship between SCA and subordinate work performance, as well as the role of information-seeking behavior in moderating the relationship between task-related uncertainty and subordinate job performance. A sample of subordinates and their supervisors from public and private sector enterprises in Pakistan were used in the study. The concept of communication apprehension is not limited to a single organization or industry, and the conditions suggest that apprehensive supervisors are likely to exist in different organizations and industries in Pakistan, including banks, telecommunications, and development sector organizations. Company directors and leaders of human resources departments were contacted to reach out to possible respondents. SmartPLS software was used to evaluate the data using a structural equation modeling technique which is commonly used in explanatory studies (Atta et al., 2021). We found evidence to support ideas predicting the association between SCA and subordinate job performance, as well as the mediating role of task-related ambiguity in the relationship. Furthermore, the findings show that information-seeking activity has a moderating effect on the link between task-related ambiguity and subordinate job performance. This is one of the first studies to look at major mediating and moderating mechanisms in the link between SCA and subordinate job performance.

• 국제학술발표논문집
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• The 9th International Conference on Construction Engineering and Project Management
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• pp.1017-1023
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• 2022

Past research shows that the construction of new infrastructure accelerates economic growth in the region by attracting more people and commodities. However, the previous studies only considered large-scale infrastructures such as sea-cross bridges and channel tunnels. There is a paucity of literature on regional infrastructure and its impact on socio-economic indicators. This paper explores the impact of new bridge construction on the human population, particularly focusing on regional bridges constructed during the 2000s in the state of Georgia. The human population at a county level was selected as a single socio-economic factor to be evaluated. A total of 124 cases were investigated as to whether the emergence of a new bridge affected the population change. The interrupted time series analysis was used to statistically examine the significance of population change due to the construction by treating each new bridge as an intervention event. The results show that, out of the 124 cases, the population of 67 cases significantly increased after the bridge construction, while the population of 57 cases was not affected by the construction at a significance level of 0.05. The 124 cases were also analyzed by route type, functional class, and traffic volume, but the results revealed, unlike large-scale infrastructure, that no clear evidence was found that a new bridge would bring an increase in the human population at a county level.

• Composites Research
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• 제18권6호
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• pp.26-33
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• 2005

손상이 발생할 경우 복합재료의 기계적 물성치는 급격한 저하를 유발한다 특히, 조류충돌, 우박, 지상 이착륙 상황에서의 타이어 조각이나 돌조각 등과 같은 작은 질량에 의한 고속충격은 구조물과 서브시스템에 심각한 손상을 유발한다. 이런 복합재 적층판에서의 손상은 기존의 전통적인 방법으로 감지하기가 어려우며, 단일 감지 기술만을 이용하여 믿을 만한 손상평가 결과를 얻을 수 없다. 본 논문에서는 고분자 압전필름 센서를 이용하여 복합 적층판에서의 충격에 의한 손상의 개시 시점 및 확장을 탐지하였다. 획득한 센서신호는 시간-주파수 분석법인 웨이블릿 변환과 단시간 푸리에 변환을 적용하였으며, 초음파 C-scan과 전자현미경을 이용하여 시편에서의 손상 확장을 검사하였다 이 연구에서는 다양한 감지기술, 특히 고분자 압전 필름센서를 이용하여 복합재 적층판에서의 고속충격 손상 특성을 확인하였다.

• 한국해안·해양공학회논문집
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• 제23권2호
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• pp.139-146
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• 2011

충격쇄파압은 권파성 파랑이 구조물 전면에 갑자기 충돌할 때 발생하며 접촉면에서 공기포켓의 생성여부에 따라 충격쇄파압의 작용특성이 달라진다. 수괴의 직접적인 충돌에 따른 Wagner형은 접촉면에서 단일 압력 첨두치를 보이는 반면, Bagnold형은 공기포켓의 진동에 의하여 비접촉면에서도 압력의 첨두치를 보이는 특성이 있다. 본 연구에서는 시공 중의 수중터널 벌크헤드의 배면(육측면)에 발생하는 충격쇄파압을 고찰하였다. Navier-Stokes 방정식을 직접 푸는 수치해석을 적용하여 벌크헤드 인근에 발생하는 쇄파를 모의한 결과, 벌크헤드의 배면에서 강한 Bagnold형 충격쇄파압이 발생함을 확인하였다. 본 충격쇄파압의 존재는 동일 조건에 대하여 수행한 수리모형실험에 의해서도 확인되었으며, 실험결과와 수치해석결과가 대체적으로 유사한 성향을 보임을 확인하였다.

• 한국산업보건학회지
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• 제33권4호
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• pp.447-454
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• 2023

Objective: This study aims to investigate the impact of changes in working conditions on job-related stress and musculoskeletal disorders using the results of seven surveys conducted at a single workplace from 2004 to 2022 regarding factors hazardous to the musculoskeletal system. Additionally, the study aims to propose alternative methods of investigating factors hazardous to the musculoskeletal system. Methods: A car parts manufacturing plant where the same survey was taken seven times from 2004 to 2022 was selected and the survey data was analyzed. The main contents of the survey were weekly working hours, Borg's scale, work intensity, job-related stress, and the prevalence of musculoskeletal symptoms. The statistical analysis was performed using SAS (version 9.4). Results: The results of this study are as follows. Firstly, changes in working conditions have an impact on job-related stress. Secondly, changes in working conditions have an impact on work intensity indicators. Thirdly, changes in working conditions have an impact on the prevalence of musculoskeletal symptoms. Fourthly, even with an increase in age and length of service, job-related stress and musculoskeletal symptoms were alleviated when working conditions were improved. Conclusions: In order for measures to reduce musculoskeletal disorders to be successful, working conditions must not deteriorate, and it is necessary to demand revisions to regulations, etc. to reflect these points in the investigation of hazardous factors to the musculoskeletal system.

• 한국가구학회지
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• 제27권3호
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• pp.237-245
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• 2016

Single households currently account for 26.5% of all households and their number is expected to continue to rise, reaching 34.5% by 2035. An analysis of the consumption trends and needs of single households shows that they are rising as a new consumer group with a focus on investment on the individual and favouring: small but high-tech products: efficient use of limited resources: safety and peace of mind: self-improvement and leisure. Products which meet such demands are having an impact on the growth of home-furnishing market. An analysis of companies in Korea's home-furnishing market, with examples like the lifestyle company IKEA, shows a variety of brands such as SPA brand, furniture specialist, distributor and character products. And yet most are OEM products which lack differentiated product lines and compete with similar display and distribution structure. We needs the Single household consumption tendency of home-furnishing market and differentiation strategy through product analysis. In order to increase the value of companies in the home-furnishing market, in addition to differentiated design, product competitiveness must aspire to higher customer satisfaction with easy assembly, innovation in logistics, innovative sales methods such as virtual-reality simulation for products and space, individually-tailored furniture for the needs of single household and products which combine smart technology. For home-grown home-furnishing brands to have competitiveness, they must leverage on the strengths of the industry, offering differentiated and competitive products in a wider range of areas with convergence functions as well as differentiation in consumer interface and application of advancing technology; in-depth product research is called for.

• 치위생과학회지
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• 제21권3호
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• pp.185-197
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• 2021

Background: This study aimed at investigating the meal regularity, health, and oral health habits of single Korean households to understand the impact of these factors on the risk of metabolic syndrome, in addition to preventing and managing metabolic syndrome. Methods: Using raw data from the 8th Korea National Health and Nutrition Examination Survey (2019), 274 study subjects, aged 19 to 64, were selected primarily from single adult households. Complex sample statistical analysis was performed using the Predictive Analytics Software Statistics ver. 18.0 program. Results: Regarding the meal regularity in single-person households in Korea, the younger group outperformed the middle-aged group, and those who drank more than once a month performed better than those who drank less than once a month. In terms of oral health, regardless of the age and the income level, participants who ate three meals a day had a higher rate of speech problems and chewing difficulties than those who ate irregularly or regularly on a regular day. Factors influencing the risk of developing metabolic syndrome were age, speech problems, and frequency of toothbrushing. Compared to the younger group, there were 0.361 times more people in the middle-aged group; and compared to those without speech problems, there were 1.161 more people with speech problem. Compared to those who tooth brushed more than four times a day, there were 1.284 more people who tooth brushed 2 to 3 times a day and there were 5.673 times more people who tooth brushed less than once. Conclusion: Based on the study results, it is necessary to implement a program that can plan and apply customized management measures and prevent metabolic syndrome by improving and correcting the health and oral health behaviors of single-person households in Korea. Therefore, active mediation measures, such as support and publicity at the local or national level, should be planned.

• 대한산업공학회지
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• 제35권3호
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• pp.203-212
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• 2009

The bullwhip effect refers to the phenomenon where demand variability is amplified when one moves upward a supply chain. In this paper, we exactly quantify the bullwhip effect for cases of seasonal demand processes in a two-echelon supply chain with a single retailer and a single supplier. In most of the previous research, some measures of performance for the bullwhip effect are developed for cases of non-seasonal demand processes. The retailer performs demand forecast with a multiplicative seasonal mixed model by using the minimum mean square error forecasting technique and employs a base stock policy. With the developed bullwhip effect measure, we investigate the impact of seasonal factor on the bullwhip effect. Then, we prove that seasonal factor plays an important role on the occurrence of the bullwhip effect.